So why are there still so many female writers?

They don't make money (unless you count government grants, and who creates those?). They don't setup franchises for future success. They're way more likely to sperg out on social media and turn fans off game before even playing.

So why do they keep getting hired?

AAAA game companies are not stupid. They may be massive corporations who don't give a whit about art or culture, but they know about money. They know how much these IPs should be making. So why do they keep doing things that lose them money? For decades?

This is not a natural cultural phenomenon; if that were the case they would have reversed course by 2020. Instead they doubled down, time and again, on ideas, styles, and policies that lose them, at first, potential revenue and, now, actual revenue. The fact that Warner, with the IPs they own, is even possibly being purchaed by the likes of Netflix is insane, but also the result of totally obvious bad decisions made over 15 years.

At some point you have to stop asking "why do they keep making bad choices?" and ask instead "why do they want games to suck?" or, better yet, "why are they willing to lose billions to do so?"